There are various circumstances under which a trolley pole must be lowered after which the vehicle on which it is mounted continues to move, either by obtaining power through another trolley pole or by using some alternative motive force. It is important to control the location of the pole as it is lowered and to keep it centered, but no suitable apparatus for this purpose exists.
In addition, it is desirable to have a convenient apparatus for raising the pole and for guiding it during the raising process so that the current collecting harp at the end of the pole is in contact with the wire to provide th motive power for the vehicle.